Why is the refund amount on my IRS CP12 letter different from what I received? Will I get the rest?

I received my tax refund on May 23, and it was more than I expected. Then, a week or so later, I received a CP12 letter dated May 28 saying that the refund estimated on my tax return was incorrect and that they owed me more money than I had listed. However, the amount on the CP12 was more than the amount that I actually received (by over double). When I went to the Where’s my refund? site, it said that I had already received my refund in the amount that was deposited.

Why would that amount have changed? I definitely don’t owe any back taxes. Is there any chance that I could expect to receive the difference sometime in the following weeks, since the letter was dated after the date I received the refund?

How others found here:

recieved a cp12 letter from the irs about my refund will it take long to recieve my refund following the letter?